In recent years, in the fields of civil engineering and construction, ultra-high-strength fiber reinforced concrete has been applied to a variety of concrete structures for the purpose of thinning and weight saving of a member, and enhancement of design freedom and enhancement of durability.
Conventionally, for example, as disclosed in Japanese Laid-open Patent Application No. H11-246255 (paragraphs [0031] to [0077]) or Japanese Laid-open Patent Application No. H05-310459 (paragraphs [0004] to [0011] and FIGS. 1 to 6), such fiber reinforced concrete is elaborated by mixing metallic fiber having a diameter of 0.16 mm-0.3 mm and a length of approximately 10 mm-18 mm in a cement matrix, which is manufactured by including aggregate having a maximum aggregate particle diameter smaller than or equal to 1 mm-2 mm and pozzolanic reactant powder as principal components and using a super plasticizer therefor, by a ratio R (=Lm/Dmax) of a mean length Lm of fiber to a maximum aggregate particle diameter Dmax larger than or equal to 10-20 and a volume of 1%-4% (see Patent Document 1 or 2, for example).